Enhancement of Soil Organic Carbon, Water Use Efficiency and Maize Yield (Zea mays L.) in Sandy Soil through Organic Amendment (Grass Peat) Incorporation

The efficient use of organic amendment (OM) is considered an economic, environmental and sustainable practice to improve soil quality, especially the accumulation of organic carbon (C) and water use efficiency (WUE) in dryland agriculture. However, the effect of different OM on soil nutrients, organic carbon fractions, water content and maize yield is unclear in arid and semi-arid regions with sandy soil. Field experiments with four OM, grass peat (GP), biochar (BC), organic fertilizer (OF) and maize straw (MS), were conducted with an equivalent amount of C input on the southeastern edge of Mu Us Sandy Land in China. Results indicated that the soil nutrients and labile organic carbon (DOC, MBC, KMnO4-C and POC) concentrations were higher under OM (GP, BC, OF and MS) treatments than in CK in the 0–0.10 m soil layers. GP treatment remarkably improved carbon pool index values (1.63, 2.51 and 2.24, respectively) in all layers compared to CK (1.00). At maturity stages of maize, the soil water content (SWC) under GP and OF treatments (11.3–13.4%) was remarkably higher than that in CK treatment (around 10.0%). Yield and WUE were remarkably greater in GP and OF treatments compared to CK. The results proved that GP amendment is superior for barren sandy soil than BC, OF and MS treatments in improving soil nutrients, organic carbon sequestration, WUE and crop yield in China.